Color temperature is a characteristic of visible light that has important applications in lighting, photography, videography, publishing, manufacturing, astrophysics, horticulture, and other fields. In practice, color temperature is only meaningful for light sources that do in fact correspond somewhat closely to the radiation of some black body, i.e., those on a line from reddish/orange to yellow to more or less white to blueish white. It does not make sense to speak of the color temperature of, e.g., a green or a purple light. Color temperature is conventionally stated in the unit of absolute temperature, the Kelvin, having the unit symbol K.
Color temperatures over 5,000K are called cool colors (bluish white), while lower color temperatures (2,700–3,000K) are called warm colors (yellowish white through red). This relation, however, is a psychological one in contrast to the physical relation implied by Wien's Displacement Law, according to which the spectral peak is shifted towards shorter wavelengths (resulting in a more blueish white) for higher temperatures.
The stars burn with white and yellow-hot heat, blue and gold bottle rockets that crackle and spark for what might as well be called forever. The intense amount of energy required to keep the flame glowing at a sustained rate is, quite literally, astronomical. The surprise twist: "cool" colors with shorter wavelengths, blueish, burn much hotter than "warm" colors; and remember, it doesn't make sense to speak of the color temperature of a green or purple light.
You can't tell at what temperature a green or purple flame burns, because those colors are simply not a part of the color temperature spectrum.
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